Co and terpolymers of styrenic monomers having reactive functional groups

ABSTRACT

Present invention provides a new class of polymeric materials having utility in the formation of self assembled polymer layers on a pretreated metallic substrate. The polymeric materials are copolymers and terpolymers of styrene and styrenic derivatives containing a reactive group selected from the group consisting of hydroxy, thiol acetoxy, thioacetoxy, thiocyanate, thiolmethyl, thioacetoxymethyl, carboxy, and mixtures thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for forming self assembledpolymer layers on a metal surface by way of coating a polymer solutiononto a treated metal substrate. Such polymer treated metal substratescan feature either hydrophobic or hydrophilic surfaces depending uponthe nature of the coated polymer layer. The polymer treated metalsubstrates also feature improved corrosion resistance. The polymertreated metal substrates further feature improved solvent resistance,chemical resistance, wettability and adhesion properties.

2. Description of the Prior Art

The surface modification of metal surface by self assembly of organicmolecules has been reported in the literature. The process of forming awell defined surfaces that moderate and mediate the chemistry of theunderlying metal using an organic molecule is often called as selfassembled monolayers as described in Macromolecules (1992), Vol. 25, (pp4730). For example, the long chain thiols or co-functional thiols onmetals like gold, silver or copper has been reported. Even though theseself assembled layers are formed by chemisorption and are thermallystable, a problem of desorption of adsorbed monolayers and exchangereactions with other derivatives in solution have been observed.

A related and relevant approach to the present invention involvesattachment of oligomers or polymers to metal surfaces by self assembly.For example, adsorption of copolymers of polystyrene-poly(propylenesulfide) on gold has been studied. Some other examples include use offilms of sulfur-derivatized polyacrylates on gold; and sulfur containingsiloxane oligomers on gold. Maleic anhydride copolymers on silver andpolyacrylic acid on aluminum oxide have also been reported. Possibleadvantages of these kinds of systems are that the anchoring of thepolymer on the solid surface by multiple attachment sites enables theformation of a more thermally and chemically stable surface.

Various types of polymeric materials are also widely used in the coatingof metals in order to improve adhesion of paints to metal surfaces, andmost importantly, to render metal surfaces corrosion resistant. Forexample, U.S. Pat. No. 4,795,506 discloses the use of solution ordispersion of poly 2,2-bis(4-hydroxyphenyl)!alkyl derivative for metalsurface coating to enhance the corrosion resistance and paint adhesioncharacteristics. U.S. Pat. No. 5,112,413 teaches the use of protectivemetal coating compositions comprising of N,N-substituted glycinehomopolymers and copolymers. U.S. Pat. No. 4,978,399 discloses variousmixtures of compositions that includes a polymer of hydroxystyrene forthe treatment of metal surfaces.

However, none of the prior art references described above disclosespolymeric compositions, which can be used to coat the metallic surfaceshaving a metal oxide layer. Most importantly, none of the referencesdescribed above discloses formation of a self assembled polymer layer ona metallic substrate using polymeric materials having reactive groups.Therefore, it is an object of this invention to provide a process forthe coating of metallic surface using novel polymeric compositionshaving reactive groups. Furthermore, an additional objective of thisinvention is to provide polymer coated metallic substrates which aremore thermally and chemically stable. Yet another objective of thisinvention is to provide a method for the formation of multiple layers ofpolymeric materials on a metallic surface by a chemical reaction of thefirst coated polymer layer with another similar or dissimilar polymericmaterial having suitable functional groups.

Prior Art

The following references are disclosed as background prior art.

U.S. Pat. No. 4,795,506 discloses processes for after treatment ofmetals using 2,2-bis(4-hydroxyphenyl)alkyl poly derivatives.

U.S. Pat. No. 5,089,064 discloses processes for corrosion resistingtreatments for aluminum surfaces.

U.S. Pat. No. 5,089,347 discloses metallized composite polymer films anda method for preparing the same.

U.S. Pat. No. 5,112,413 discloses a method for treating metal surfaceswith a polymer solution.

U.S. Pat. No. 5,242,714 discloses processes for forming protective basecoatings on metals.

U.S. Pat. No. 5,246,507 discloses processes for metal surface treatmentusing aqueous polymeric solutions.

U.S. Pat. No. 5,281,282 discloses compositions and a process fortreating metal.

U.S. Pat. No. 5,298,289 discloses polyphenol compounds and treatment andafter treatment of metal, plastic and painted surfaces therewith.

U.S. Pat. No. 5,330,627 discloses thermosetting coating compositions andtheir use.

U.S. Pat. No. 5,385,616 discloses a method for inhibiting corrosion of ametal surface by formation of iron carboxylate.

U.S. Pat. No. 5,449,415 discloses compositions and a process fortreating metals.

Macromolecules (1992), Vol. 25, (pp 4730) discloses the use of longchain thiols or ω-functional thiols for treating metals like gold,silver or copper.

Polymer (1981), Vol. 22, (pp 361) also discloses the use of thiols forsurface treatment of metals like gold, silver or copper.

Macromolecules, (1988), Vol. 21, (pp 1204-1208) discloses an adsorptionof copolymers of polystyrene-poly(propylene sulfide) on gold.

Langmuir, (1993), Vol. 9, (pp 3200-3207) discloses the use of films ofsulfur-derivatized polyacrylates on gold.

Macromolecules, (1993), Vol. 26, (pp 1230-1237) discloses the use offilms of sulfur-derivatized polyacrylates on gold.

Langmuir, (1991), Vol. 7, (pp 1558) discloses the use of films ofsulfur-derivatized polyacrylates on gold.

Macromolecules, (1994), Vol. 27, (pp 3053-3062) discloses theapplication of sulfur containing siloxane oligomers on gold.

Proc. 1st Pacific Polym. Conf. (1989), (pp 460) discloses the use ofMaleic anhydride copolymers on silver.

ACS Polym. Prepr., (1990), Vol. 31, (pp 550) discloses the use ofpolyacrylic acid on aluminum oxide.

All of the references described herein are incorporated herein byreference in their entirety.

SUMMARY OF THE INVENTION

It has now been found that a self assembled polymer layer can be readilyformed on a pretreated metallic surface having a metal oxide layer onthe surface. In fact, the polymer layer so formed permanently adheres tothe base metallic surface thus offering improved corrosion resistance,wettability, solvent resistance, thermal resistance, and adhesioncharacteristics.

The process of the present invention comprises the steps of: a)preparing a metallic substrate by treating (cleaning) such that areactive zerovalent metal or metal oxide layer is exposed; b) preparinga solution or a dispersion of a novel polymeric material by dissolvingor dispersing the polymeric material in a solvent, the polymer beingcharacterized by having recurring combinations consisting essentially ofacyclic, cyclic and aromatic mutivalent moieties at least one of whichcontains a reactive substituent independently selected from the groupconsisting of --OH, --OCOR, --SH, --SCOR, --CH₂ SH, --CH₂ SCN, --CH₂SCOCH₃, --COOH, --COOR, and mixtures thereof, where R is an aliphatic,alicyclic, or an aromatic moiety containing 1 to about 20 carbon atoms;and c) contacting said metallic substrate with said solution ordispersion for a sufficient period of time and at suitable temperatureand pressure conditions to form at least one layer of polymeric materialon said metallic substrate.

In another aspect of this invention the polymeric materials of thisinvention are novel polymeric compositions.

DETAILED DESCRIPTION OF THE INVENTION

It has now been found that a self assembled polymer layer can be readilyformed on a pretreated metallic surface having a metal oxide layer onthe surface. In fact, the polymer layer so formed permanently adheres tothe base metallic surface thus offering improved corrosion resistance,wettability, solvent resistance, thermal resistance, and adhesioncharacteristics.

The process of the present invention comprises the steps of: a)preparing a metallic substrate by treating (cleaning) such that areactive zerovalent metal or metal oxide layer is exposed; b) preparinga solution or a dispersion of a novel polymeric material by dissolvingor dispersing the polymeric material in a solvent, said polymer beingcharacterized by having recurring combinations consisting essentially ofacyclic, cyclic and aromatic multivalent moieties at least one of whichcontains a reactive substituent independently selected from the groupconsisting of--OH, --OCOR, --SH, --SCOR, --CH₂ SH, --CH₂ SCN, --CH₂SCOCH₃, --COOH, --COOR, and mixtures thereof, where R is an aliphatic,alicyclic, or an aromatic moiety containing 1 to about 20 carbon atoms;and c) contacting said metallic substrate with said solution ordispersion for a sufficient period of time and at suitable temperatureand pressure conditions to form at least one layer of polymeric materialon said metallic substrate.

Accordingly, the metallic substrates for the purpose of this inventionare in the form of a film, sheet, foil, wire, wafer, tube, fiber, or arod. Most forms of metallic substrates are in the form of a film, sheet,wafer, foil, or a rod.

The metallic substrate is selected from the group consisting of copper,silver, gold, aluminum, zinc, iron, steel, stainless steel, and mixturesthereof. Preferred metallic substrates are copper, iron, steel,stainless steel and aluminum.

The metallic substrates can also be metallized non-metallic substrates.Representative examples of non-metallic substrates include silicon waferand a variety of plastic materials known in the art. Specific examplesof plastic materials may be selected from the group consisting ofpolyethylene, polypropylene, polystyrene, polyolefins, cellophane,polyethylene terephthalate, nylon, polyvinyl chloride, and mixturesthereof. Preferred non-metallic substrates are silicon wafer and filmsof polyethylene terephthalate, polyethylene, and polypropylene. Thepreferred non-metallic substrate is a silicon wafer.

The metallization of non-metallic substrate may be carried out by any ofthe techniques well known in the art. In one preferred embodiment, thegold is deposited on a silicon wafer using an electron beam deposition.Using this technique, first a layer of about 200 Å thickness titanium isdeposited on a polished silicon wafer, and then a layer of gold of about2000 Å thickness is deposited.

The metallization of plastic materials can also be effected byconventional metallizing techniques--for example, by deposition from asuspension of finely divided metallic particles in a suitable liquidvehicle, or by a electron beam evaporation, electroless plating, or by avacuum deposition process, in which a metal is evaporated onto theadherent polymeric resin surface in a chamber maintained underconditions of high vacuum.

In a typical metallic surface treatment operation employing thisinvention, the metallic substrate to be treated is initially treated bya chemical or physical process and then water rinsed to remove greaseand dirt from the surface. The purpose of treating the metal surface isto have a zerovalent metal or metal oxide exposed on the surface.Various different physical and chemical methods well known in the artmay be used to treat the metallic substrate of this invention. Suchexamples include acid wash, base wash, treatment with metal phosphatesolutions, extracting with organic solvents, heating to hightemperatures, and subjecting metal surface to an open flame. Forexample, a metallized silicon wafer metallized with gold is cleaned bytreating the wafer with "piranha" solution (a 3:1 mixture of sulfuricacid and 30% hydrogen peroxide). Whereas a preferred method to clean analuminum foil is to extract the foil in toluene for several hours,preferably for about 8 hours to 30 hours, and then to heat the foil toaround 220° C. to 250° C. for several days, preferably for about 3 to 5days. Thus, as mentioned hereinabove, various physical and chemicalmethods known in the art may be used to treat/clean the metallic surfaceof this invention.

The polymeric material suitable for the formation of self assembledlayer on a metallic substrate may be derived from a variety ofstructures including acyclic, cyclic, or aromatic multivalent moieties.Each of the acyclic, cyclic, or aromatic multivalent moietiesadditionally contains at least one reactive substituent independentlyselected from the group consisting of --OH, --OCOR, --SH, --SCOR, --CH₂SH, --CH₂ SCOCH₃, --COOH, --COOR, and mixtures thereof. Where R is analiphatic, alicyclic, or an aromatic moiety containing 1 to about 20carbon atoms.

Illustrative of acyclic structures that are suitable as polymericmaterials of this invention include unsaturated C₁ through C₁₀ straightchain or branched aliphatic units capable of forming polymers such asethylene, propylene, butylene, pentalyene, and the like. Illustrative ofcyclic structures suitable for forming the polymeric materials of thisinvention include cyclohexylene, vinyl cyclohexane, norbornylene,bornylene, cyclopentalene, cycloheptalene, and the like. Illustrative ofaromatic structures are phenylene, biphenylene, naphthalene, pyridine,pyrazine, furan, thiophene, pyran, and the like.

The preferred polymeric material of the present invention has theformula: ##STR1## wherein Ar¹, Ar² and Ar³ are each independentlyselected from the group consisting of phenylene, biphenylene, pyridine,naphthylene, quinolyene, pyrazine, furan, thiophene, pyran and mixturesthereof. At least one of the hydrogen atoms on said moieties Ar¹, Ar²,and Ar³ may be replaced with reactive substituents independentlyselected from the group consisting of --OH, --OCOR, --SH, --SCOR, --CH₂SH, --CH₂ SCN, --CH₂ SCOCH₃, --COOH, --COOR, --CH₂ O(PEG)_(d) OCH₃,--CH═CH₂, and mixtures thereof, where PEG is a polyethylene glycolmoiety, d is the molecular weight of the polyethylene glycol moiety andmay range from about 200 to about 10,000, and R is an aliphatic,alicyclic, or an aromatic moiety containing 1 to about 20 carbon atoms.

Optionally, one or more of the hydrogen atoms on said aromatic moietiesAr¹, Ar², and Ar³ moieties may additionally be replaced withsubstituents, each independently selected from the group consisting ofBr, F, Cl, I, phenyl, tolyl, alkyl, and fluoroalkyl groups having theformula C_(n) H_(x) F_(y), where n is an integer from 1 to 4, x and yare integers from 0 to 2n+1, and the sum of x and y is 2n+1.

In a preferred polymeric material, the Ar¹, Ar², and Ar³ moieties areunsubstituted except that at least one of the hydrogen atoms is replacedin these moieties with a reactive group as mentioned above. a, b, and cin the above structure represent mole precents of said moieties Ar¹, Ar²and Ar³, where a+b+c=100.

Examples of more preferred polymeric materials of this invention whichare novel compositions are phenylene moieties of the formula: ##STR2##wherein X is a reactive substituent as described above and is selectedfrom the group consisting of --OH, --OCOR, --SH, --SCOR, --CH₂ SH, --CH₂SCN, --CH₂ SCOCH₃, --COOH, --COOR, and mixtures thereof, where R is analiphatic, alicyclic, or an aromatic moiety containing 1 to about 20carbon atoms. Wherein Y may be X or --CH₂ O(PEG)_(d) OCH₃ or --CH═CH₂,where PEG is a polyethylene glycol moiety and d represents molecularweight of said polyethylene glycol moiety, which ranges from about 200to about 10,000. Optionally, one or more of the hydrogen atoms on thephenylene units may additionally be replaced with substituentsindependently selected from the group consisting of Br, F, Cl, I,phenyl, tolyl, alkyl, and fluoroalkyl groups having the formula C_(n)H_(x) F_(y), where n is an integer from 1 to 4, x and y are integersfrom 0 to 2n+1, and the sum of x and y is 2n+1. Preferably the phenyleneunits are unsubstituted except for the reactive group, X present on oneof the phenylene units and moiety Y present on one of the other twophenylene units as mentioned hereinabove.

a, b, and c represent mole percents of said repeating units, where a isfrom about 0% to about 95%, b is from about 5% to about 100%, and c isfrom about 0% to about 45%.

Preferred phenylene units are selected from the group consisting ofstyrene, 2-hydroxystyrene, 4-hydroxystyrene, 2-methyl-4-hydroxystyrene,3-methyl-4-hydroxystyrene, 2-acetoxystyrene, 4-acetoxystyrene,2-methyl-4-acetoxystyrene, 3-methyl-4-acetoxystyrene, 2-mercaptostyrene,4-mercaptostyrene, 2-methyl-4-mercaptostyrene,3-methyl-4-mercaptostyrene, 2-thioacetoxystyrene, 4-thioacetoxystyrene,2-thioacetoxymethylstyrene, 4-thioacetoxymethylstyrene,2-methyl-4-thioacetoxystyrene, 3-methyl-4-thioacetoxystyrene,2-thiocyanatomethylstyrene, 4-thiocyanatomethylstyrene,2-methyl-4-thiocyanatomethylstyrene,3-methyl-4-thiocyanatomethylstyrene, 4-thiolmethylstyrene,2-thiolmethylstyrene, 2-methyl-4-thiolmethylstyrene,3-methyl-4-thiolmethylstyrene, 4-trifluoroacetoxystyrene, vinyl benzylchloride, vinyl benzyl trichloroacetate, a styrenic derivative havingthe structure: ##STR3## and mixtures thereof, wherein Y may be X or--CH₂ O(PEG)_(d) OCH₃ or --CH═CH₂, where PEG is a polyethylene glycolmoiety and d represents molecular weight of said polyethylene glycolmoiety, which ranges from about 200 to about 10,000.

Most preferably the phenylene units are selected from the groupconsisting of styrene, 2-hydroxystyrene, 4-hydroxystyrene,2-acetoxystyrene, 4-acetoxystyrene, 4-mercaptostyrene,4-thioacetoxystyrene, 4-thioacetoxymethylstyrene,2-thiocyanatomethylstyrene, 4-thiocyanatomethylstyrene,4-thiolmethylstyrene, vinyl benzyl chloride, a styrenic derivativehaving the structure: ##STR4## and mixtures thereof, wherein Y may be Xas described hereinabove or --CH₂ O(PEG)_(d) OCH₃ or --CH═CH₂, where PEGis a polyethylene glycol moiety and d represents molecular weight ofsaid polyethylene glycol moiety, which ranges from about 200 to about10,000.

The preferred polymers described herein are made by an additionpolymerization of the preferred phenylene units described hereinabove.The preparation of addition polymers are well known in the art, and maybe made readily by free radical, or cationic, or anionicpolymerizations. Preferred method for making these polymers is by freeradical polymerization which is well known in polymer chemistry. Usingfree radical polymerization techniques, the novel polymers of thepresent invention may be made by bulk, solution, suspension, or emulsionpolymerization processes following the procedures well known in the art.Examples of such polymerization processes are described in U.S. Pat. No.4,678,843; U.S. Pat. No. 4,689,371; U.S. Pat. No. 4,775,730; and U.S.Pat. No. 4,822,862, which are hereby incorporated herein by reference intheir entirety.

The homopolymers, copolymers, and terpolymers of this invention may beprepared by a free radical solution polymerization. A free radical typeof polymerization initiator or "catalyst" is generally employed whichcan be an azo compound such as 2,2'-azobis(2,4-dimethylvaleronitrile)(sold by du Pont as "VAZO-52"), 2,2'-azobisisobutyronitrile (AIBN; soldby du Pont as "VAZO-64"), 2,2'-azobis(methylbutyronitrile) (sold by duPont as "VAZO-67"), and 1,1'-azobis(cyanocyclohexane) (sold by du Pontas "VAZO-88"). Other free-radical polymerization initiators which may beused are peroxy compounds, e.g., benzoyl peroxide and potassiumpersulfate, and peresters and peroxyketals. Generally usedpolymerization initiator is an azoinitiator, AIBN.

The preferred polymers of the present invention may be homopolymers,copolymers, or terpolymers. Examples of preferred homopolymers arepoly(4-acetoxystyrene), poly(4-hydroxystyrene),poly(4-thioacetoxystyrene), poly(4-mercaptostyrene),poly(4-thioacetoxymethylstyrene), poly(4-thiolmethylstyrene), andpoly(4-thiocyanatomethylstyrene). Most preferred homopolymers arepoly(4-acetoxystyrene), and poly(4-hydroxystyrene). Preferred copolymerscontain styrene as one of the comonomers, and the other monomer is astyrenic derivative containing the reactive group mentioned hereinabove.Most preferred copolymers are derived from styrene and one of themonomers selected from the group consisting of4-thioacetoxymethylstyrene, 4-thiocyanatomethylstyrene,4-thiolmethylstyrene, 4-acetoxystyrene, 4-hydroxystyrene, and4-trifluoroacetoxystyrene.

Similarly, preferred terpolymers of the present invention consists ofstyrene as the first monomer, styrenic derivative consisting of areactive group as the second monomer, and a third monomer derived fromvinyl benzyl chloride, vinyl benzyl trichloroacetate, which can furtherbe functionalized by a polyethylene glycol moiety.

Within the copolymer, the molar ratio of styrene to the reactivestyrenic monomer can be 1:99 to 99:1, preferably 60:40 to 40:60, andmore preferably 90:10 to 10:90. Within the terpolymer, the molarpercents of each of the monomers--styrene, reactive styrenic monomer,and vinyl benzyl chloride derivative--can range from 1 to 98, andpreferably 25 to 50. Most preferred molar ratio ranges from about60:20:20 to about 90:5:5.

The molecular weights of the polymers used in the present invention maybe in the range of from about 2,000 to about 100,000 or greater,preferably the molecular weight range is in from about 3,000 to about80,000, and more preferably from about 4,000 to about 60,000.

The polymeric material is dissolved or dispersed in a suitable organicsolvent or in water. The organic solvents that can be used fordissolving or dispersing the polymeric material may be selected from thegroup consisting of acetonitrile, methyl alcohol, ethyl alcohol,acetone, methyl ethyl ketone, t-butyl methyl ketone, ethyl acetate,t-butyl acetate, toluene, chloroform, methylene chloride,tetrachloroethylene, and mixtures thereof. The preferred organicsolvents are acetonitrile, toluene, acetone, chloroform, methyl alcohol,and mixtures thereof.

The polymeric materials of the present invention may generally be usedin surface treatment solutions over a wide range of concentrations. Itwill be appreciated that the levels of use or useful ranges will varywith many factors well known to the skilled artisan. Useful levels ofthe polymeric compositions of the present invention dissolved ordispersed in a solvent may be in the range of from about 0.0001 weight %to about 30 weight %, based on the total weight of the composition.Preferably, the concentration of the solution is in the range of fromabout 0.001 weight % to about 15 weight %, and more preferably 0.01weight % to 10 weight %.

Application of the polymeric compositions of the present invention inthe contacting step to a metallic substrate can be carried out by anyconventional method. For example, the polymeric composition can beapplied by spray coating, roller coating, or dipping. The preferredmethod of application of the polymeric composition is by dipping. Thetemperature of the solution applied can vary over a wide range, but ispreferably from about 25° C. to about 80° C. The pressure in thisapplication step is not critical and can be subatmospheric, atmospheric,or super atmospheric. After application of the polymer solution to themetallic surface, the surface can optionally be rinsed with the samesolvent used for dissolving the polymeric material. 4-hydroxystyrene,4-acetoxystyrene, and 4-trifluoroacetoxystyrene. The contactingtemperature of the aluminum foil in the polymer solution is from about25° C. to about 80° C., preferably from about 25° C. to about 60° C.

An important advantage derived from the practice of the presentinvention is the use of relatively dilute solutions of the polymericmaterials having reactive groups to coat a metallic surface to form astable polymeric layer on the metallic surface. Another importantadvantage derived from the practice of the present invention is that thepolymeric layer so formed on a metallic surface can further be reactedwith another functional molecule such that the surface characteristicsof the metallic substrate can be regulated to form either a hydrophobicor a hydrophilic surface.

The polymeric treatment process according to this invention is useful intreating a metallic substrate to form surfaces that feature eitherhydrophobic or hydrophilic surfaces. Such surfaces also feature improvedcorrosion resistance, solvent resistance, and chemical resistance. Inaddition, such treated substrates also feature improved wettability andadhesion properties.

This invention is further illustrated by the following examples whichare provided for illustration purposes and in no way limit the scope ofthe present invention.

EXAMPLES (GENERAL)

In the Examples that follow, the following abbreviations are used:

PS--Polystyrene

PAS--Poly(4-acetoxystyrene), a homopolymer.

PHS--Poly(4-hydroxystyrene), a homopolymer.

POSAC--A copolymer of styrene and 4-thioacetoxymethylstyrene.

POSCN--A copolymer of styrene and 4-thiocyanatomethylstyrene.

POSH--A copolymer of styrene and 4-thiolmethylstyrene.

P(SAS)--A copolymer of styrene and 4-acetoxystyrene.

P(SHS)--A copolymer of styrene and 4-hydroxystyrene.

P(STFAS)--A copolymer of styrene and 4-trifluoroacetoxystyrene.

PEG--Polyethylene glycol.

PSPEVB1SCN--A terpolymer of styrene, 4-thiocyanatomethylstyrene, andvinyl benzyl polyethylene glycol, where molecular weight of thepolyethylene glycol moiety is 2000, and termed PEG₂₀₀₀.

After polymer application, the treated metallic surface is optionallydried. Drying can be carried out, for example, in an oven under anitrogen atmosphere. While room temperature drying can be employed, theuse of elevated temperatures is preferred to decrease the amount ofdrying time required.

In one specific embodiment of the present invention, the polymer treatedmetallic substrate produces a hydrophobic surface. The hydrophobicity(or hydrophilicity) of the surface may be measured by a variety oftechniques well known in the art. In this embodiment, the hydrophobicityof the metallic surface was measured by contact angle goniometricmeasurements.

The surface characteristics of the metallic surface can further bealtered by contacting the metallic surface with various other functionalmolecules which are similar or dissimilar to the polymeric materials ofthe present invention. Examples of functional molecules that can be usedto regulate the surface characteristics of the metallic substratesinclude acrylic acid, methacrylic acid, acrylonitrile,methacrylonitrile, acrylamide, vinyl acetate, t-butyl acrylate, methylacrylate, ethyl acrylate, dimethyldichlorosilane,1,6-diisocyanatohexane, sodium salt of monomethoxy poly(ethyleneglycol), and mixtures thereof.

In this specific embodiment, the subsequent treatment with a functionalmolecule also may be carried out in the presence of an initiator whichis capable of grafting the functional molecule onto the polymericmaterial coated onto the metallic substrate in the contacting step.Various initiators well known in the art that can affect such graftingcan be used. Specific classes of initiators used in the art includephoto, thermal, or acid initiators. Photoinitiators are especiallypreferred for such grafting.

In another specific embodiment, the polymer treated metallic substratein accordance with the present invention can further be cured byirradiation using any high energy radiation source well known in theart. Preferred radiation sources are X-rays and UV, and more preferablythe polymer treated samples are irradiated using an X-ray source.

In another preferred embodiment, aluminum foil is treated by extractingwith toluene for 24 hours and then heated to about 235° C. andmaintained at that temperature for 4 days. The aluminum foil sotreated/cleaned is then contacted with a polymeric solution formed bydissolving a copolymer either in toluene or acetonitrile. The copolymersused in this preferred embodiment are formed from styrene and a monomerselected from the group consisting of

PSPEVB 1SAC--A terpolymer of styrene, 4-thioacetoxymethylstyrene, andvinyl benzyl polyethylene glycol, where molecular weight of polyethyleneglycol moiety is 2000, and termed PEG₂₀₀₀.

P(SASVBC)--A terpolymer of styrene, 4-acetoxystyrene, and vinyl benzylchloride.

P(SASVBOCOCCl₃)--A terpolymer of styrene, 4-acetoxystyrene, vinyl benzyltrichloroacetate.

DMF--N,N'-dimethylformamide

THF--Tetrahydrofuran

AIBN--2,2'-Azobisisobutyronitrile.

NMR--Nuclear magnetic resonance spectroscopy, usually of either proton,¹ H, and/or carbon 13, ¹³ C.

IR--Infrared spectroscopy.

XPS--X-ray photoelectron spectroscopy

The homopolymers, copolymers, and terpolymers of the present inventionmay be prepared by the methods well known in the art. However,illustrative procedures for the synthesis of a few of the copolymers andterpolymers are provided below.

EXAMPLE A Preparation of copolymer of styrene and4-thiocyanatomethylstyrene--Molar ratio 90:10

3.06 g (0.018 mol) of 4-thiocyanatomethylstyrene and 64.0 mg (0.4 mmol)of AIBN were taken in a three necked flask fitted with a refluxcondenser, and purged continuously with argon. The flask was evacuatedunder aspirator pressure and backfilled with nitrogen three times. Tothis mixture was added 200 mL of distilled toluene followed by 20 mL(0.1 8 mol) of distilled styrene. The contents of the flask was thenheated to 100° C. in an oil bath and maintained at that temperature fora period of about 24 hours. At the end of this period, the contents ofthe flask were allowed to cool to room temperature and the contents wereprecipitated from 1400 mL of methanol. The precipitate was separated byfiltration and dried to yield the copolymer (9.5 g). The structure ofthe produced copolymer was verified by ¹ H and ¹³ C NMR, and IRspectroscopy. The molecular weight, M_(v), of the copolymer asdetermined by the viscosimetric measurements was 41,700.

Various other copolymers disclosed herein may be synthesized similarlyusing the procedure described above.

EXAMPLE B Preparation of terpolymer of styrene,4-thiocyanatomethylstyrene, and vinyl benzyl polyethylene glycol

The terpolymers of the present invention were synthesized using a threestep approach as detailed below:

Step I: Following the procedure as outlined in Example A, a copolymer ofstyrene and vinyl benzyl chloride of 85:15 molar ratio was prepared.

Step II: A terpolymer of styrene, vinyl benzyl chloride, and vinylbenzyl polyethylene glycol was prepared as follows: 1 g (0.04 mol) ofdry sodium was stirred with 0.3 g (2.34 mmol) of naphthalene dissolvedin 15 mL of THF for 10 hours at room temperature. The green solution ofnaphthalene-sodium was separated from the excess sodium by cannulation.This solution was then mixed with 2.3 g of PEG₂₀₀₀ dissolved in 10 mL ofTHF, and the combined mixture was stirred for 10 minutes during whichtime the solution had turned light green in color. To this mixture wasadded 8 g of the copolymer, from Step I, dissolved in 40 mL of THF bycannula and the contents were stirred for an additional period of about75 minutes. At the end of this period, the contents were concentrated invacuo to yield a hard white solid that was Soxhlet extracted with methylalcohol overnight to remove the excess PEG. As the extracted solid couldnot be precipitated in any suitable solvent it was dissolved indichloromethane. Concentration of this solution in vacuo yielded theterpolymer as a crystalline material. The structure of the so formedterpolymer was verified by ¹ H and ¹³ C NMR, and IR spectroscopy. Themolecular weight, M_(v), of the terpolymer as determined by theviscosimetric measurements was 56,600.

Step III: The desired terpolymer of styrene, 4-thiocyanatomethylstyrene,and vinyl benzyl polyethylene glycol was synthesized from the terpolymerof Step II as follows: 1.5 g of the terpolymer formed in Step II wasmixed with 350 mL of toluene taken in a 500 mL flask and the contentsstirred. To this mixture was added 1.2 g of potassium thiocyanatedissolved in 115 mL of a solvent mixture of DMF and acetone (100/15,v/v). The entire contents of the flask was then heated and allowed toreflux for about 30 hours. The contents were then allowed to cool toroom temperature at which time slightly turbid mixture becamehomogeneous. The solvents were evaporated under vacuo and the residualsolids were precipitated from water. The precipitate was washed withmethanol and dried to yield a white powder of the terpolymer (0.9 g).The structure of the produced terpolymer was verified by ¹ H and ¹³ CNMR, and IR spectroscopy.

Various other terpolymers of the present invention may be synthesizedusing the procedures described in Step I through III of Example B withappropriate modifications so as to form the terpolymers consisting ofdifferent reactive groups.

General Analytical Techniques Used for the Polymer Modified SurfaceAnalysis

A variety of analytical techniques were used to study the polymermodified metallic substrates which included the following:

XPS Spectroscopy: The chemical composition in the top 50-100 Å of thesurface was assayed by XPS spectroscopic analysis.

Reflectance IR Spectroscopy: The presence of the polymeric overlayerswas confirmed by reflectance IR studies. Analysis of very thin coatingsin the nanometer range is normally done at an incident angle of 80°.

Contact Angle Goniometry: The contact angle measurements analyzed thetop 5 Å of the surface and provided information about the hydrophobicityor hydrophilicity of the surface.

Example 1

The polymeric layers on gold wafers were formed using the followingprocedure:

Preparation of Gold Wafers: The gold wafers were prepared by electronbeam deposition of 100 Å of titanium and 2000 Å of gold onto polishedsilicon single crystalline wafers.

Cleaning of Gold Wafers: Prior to the formation of polymeric layers ongold wafers, the gold wafers were cleaned as follows: The gold wafer wasdiced into 1×1 cm² size wafers. These were taken in 20 mL reaction vialsand treated with "piranha" solution (a 3:1 mixture of sulfuric acid and30% hydrogen peroxide) for about 5 to 10 seconds. CAUTION: this mixtureis extremely corrosive and should be used with caution as it reactsviolently with most organic materials. The wafers were then washedcopiously with deionized water and then blown dry with nitrogen.

Preparation of Polymer Solution: The copolymers as listed in Table Iwere dissolved in chloroform so that solutions containing 0.01 to 10weight percent polymer were prepared.

Treatment with Polymeric Solution: The cleaned and dried gold waferswere immediately treated with the polymer solution taken in 20 mLreaction vials. All of the polymers used in this Example were copolymersas listed in Table 1, and were dissolved in chloroform. All adsorptionsof polymeric materials were done for 22 hours at room temperature. Afterthe allowed time for adsorption of the polymeric material onto a surfaceof the gold wafer, the wafers were rinsed copiously with chloroform, thesolvent used to dissolve the polymeric material, and then blown dry withnitrogen. A control experiment was also carried out with a gold waferthat was immersed in chloroform for 22 hours (Run No. 1, Table 1). Thewafers were then analyzed by XPS. The results are summarized in Table 1.

                  TABLE 1                                                         ______________________________________                                                   Composition                                                                   (mol %)                                                                       (styrene:other                                                                         Atomic percentages (%)                                    Run No.                                                                              Copolymer monomer)   Au   S    C    O                                  ______________________________________                                        1      Starting Au                                                                             --         25.2 0.0  62.3 12.3                                      wafer                                                                  2      POSH      95:5       9.4  1.5  82.6 6.2                                3      POSH      90:10      3.8  1.2  91.4 2.9                                4      POSCN     95:5       16.5 2.5  73.2 7.5                                5      POSCN     90:10      16.7 3.5  75.2 5.6                                6      POSAC     90:10      17.9 5.2  68.4 8.4                                ______________________________________                                    

It is quite apparent from these results that the polymeric layers areformed on gold wafers. In fact, the amount of sulfur on the surface isincreased when the amount of sulfur functionality in the copolymer isincreased as evidenced by Run Nos. 3, 5, and 6.

Example 2

This example illustrates the application of polymeric materials onto acleaned surface of a metallic foil thereby forming polymeric layers onthe foil surface.

Preparation of Metallic Foil for Polymer Treatment: The metallic foilused in this Example 2 was a copper foil. The copper foil (1 mm thick)was heated to red hot in a flame, quickly transferred to a flask, andallowed to cool under a nitrogen flow. This copper foil was thenimmersed in 12% nitric acid (12 g of nitric acid diluted in 100 mL ofdistilled water), and the foil is etched in a sonicator for 5 minutes.The foil was removed and then copiously washed with deionized water andblown dry with nitrogen.

The polymer solutions for treatment of the copper foil were preparedfollowing the procedure given in Example 1. The polymer adsorptionexperiments were also carried out in accordance with the procedures setforth in Example 1 with the exception that the adsorption experimentswere carried out for a period of 16 hours at room temperature. Thepolymer treated samples were analyzed by XPS spectroscopy. The resultsare summarized in Table 2. A control experiment (Run No. 1) was alsocarried out wherein the copper foil was not treated with a polymersolution, but was immersed in chloroform for 16 hours (Run No. 1, Table2).

                  TABLE 2                                                         ______________________________________                                                       Composition                                                                   (mol %)                                                        Run            (styrene:other                                                                           Atomic percentages (%)                              No.  Copolymer monomer)   Cu   S    C    O    N                               ______________________________________                                        1    Starting Cu                                                                             --         6.7  0.0  36.6 46.8 9.8                                  foil                                                                     2    POSH      95:5       4.0  1.0  58.1 31.6 5.4                             3    POSH      90:10      0.5  0.9  89.4 7.3  1.6                             4    POSCN     95:5       5.6  0.2  47.1 38.2 8.9                             5    POSCN     90:10      5.2  0.2  50.0 38.6 5.9                             6    POSAC     90:10      6.0  0.0  38.6 48.7 6.8                             ______________________________________                                    

It is apparent from these results that carbon contents on the copperfoil increased in all cases after polymer treatment, thus evidencing theformation of polymeric layers on the surface of copper foil. Inaddition, an increase in the level of sulfur derivatized monomer in thecopolymer generally increased the level of carbon (Run Nos. 3 and 5).

Example 3

This Example illustrates the effect of temperature on the level ofadsorption of polymeric material during the polymer contacting step.

The procedure of Example 2 was essentially followed except that thecontacting step was carried out at 57° C. for a period of 16 hours. Thecopolymer used was a 90:10 composition of POSCN. The atomic percentageson the surface of the copper foil so treated as determined by XPSanalysis were as follows: Cu--5.2%, S--0.7%, C--61.3%, O--24.7%, andN--8.1%. This clearly shows that higher levels of polymeric materials onthe surface of copper foil can be attained by carrying out theadsorption experiments at higher temperatures; 50.0% of carbon at roomtemperature vs. 61.3% at 57° C.

Example 4

This Example illustrates the effect of adsorption time on the level ofpolymeric material on the surface of copper foil.

The procedures of Example 2 were followed except for the followingmodifications. Two cleaned copper foils were treated separately with 20mL of chloroform solutions (0.01 g/mL) of POSH (95:5 molar ratio) andPOSCN (95:5 molar ratio) taken in two separate vials for a period of 3days in both cases. The XPS spectroscopic analysis of these foils showeda higher carbon content than that obtained with foils contacted atlesser adsorption time of 16 hours. The extent of this increase wasgreater for the POSH copolymer. The carbon content increased from 58.1%to 73% for POSH copolymer, and 47.1% to 54% for POSCN copolymer. Acontrol experiment wherein copper foil was immersed in chloroform for 3days was also carried out. The carbon content on this foil was unchangedand remained at 37% as in Run No. 1, Example 2.

Example 5

The procedures of Example 2 were followed except for the followingmodifications. The polymers employed were terpolymers: PSPEVBISCN(styrene:4-thiocyanatomethylstyrene:vinyl benzyl polyethylene glycolmonomer=80:10:10 molar ratio), and PSPEVB1SAC(styrene:4-thioacetoxymethylstyrene:vinyl benzyl polyethylene glycolmonomer=80:10:10 molar ratio). These terpolymers were dissolved intoluene at a concentration of 0.01 g/mL. The adsorption experiments werecarried out using 20 mL of these toluene solutions at 25° C. for aperiod of 38 hours. The treated foils were washed in a stream of tolueneand blown dry with nitrogen. The results from the XPS analysis are givenin Table 3. Two control experiments are also listed in Table 3; onecontrol was carried out by simply immersing copper foil in toluene for aperiod of 38 hours (Run No. 1, Table 3), and a second control wascarried out by immersing copper foil in a solution of polystyrene intoluene (0.01 g/mL of polystyrene in toluene; Run No. 2, Table 3).

                  TABLE 3                                                         ______________________________________                                                        Composition                                                                   (mol %)                                                       Run             (styrene  Atomic percentages (%)                              No.  Terpolymer M.sub.1.sup.a :M.sub.2.sup.b)                                                           Cu   S    C    O    N                               ______________________________________                                        1    Starting Cu                                                                              --        9.3  0.0  38.6 38.9 13.1                                 foil                                                                     2    PS         --        4.0  0.0  57.6 26.5 10.2                            3    PSPEVB1SAC 80:10:10  2.1  2.1  74   19   2.6                             4    PSPEVB1SCN 80:10:10  1.9  0.7  72   20   5.1                             ______________________________________                                         .sup.a M.sub.1 is a sulfur derivatized monomer;                               .sup.b M.sub.2 is a vinyl benzyl polyethylene glycol monomer.            

It is apparent from theses results that increased adsorption ofterpolymers on the surface of copper foils were observed as evidenced bythe increased carbon contents on the surface of the copper foils.

Example 6

This Example illustrates the formation of polymeric layers on analuminum foil. The procedures as set forth in Example 2 were used exceptfor the following modifications. The aluminum foil was cleaned byextraction with toluene for 24 hours and then heated to 235° C. for 4days to produce a clean surface. Homopolymers, PAS and PHS, andcopolymers, P(SAS), P(SHS), and P(STFAS) were used for the treatmentstudies with aluminum foil. All of the polymers were dissolved intoluene at a concentration of 0.7 to 8.0 weight percent in tolueneexcept for PHS. PHS was dissolved in acetonitrile at a concentration of0.01 g of PHS in 20 mL of acetonitrile. The adsorption experiments werecarried out for a period of about 24 hours in all cases. The polymertreated aluminum foils were then analyzed by XPS spectroscopy and bycontact angle measurements. The results are summarized in Table 4.

                  TABLE 4                                                         ______________________________________                                                                             Contact                                                  Composition                                                                              Atomic    Angle                                    Run             (mol %)    percentages (%)                                                                         (Θa.sub.(max),                     No.  Polymer    (styrene:M.sub.1.sup.a)                                                                  Al    C     degree)                                ______________________________________                                        1    Starting Al foil                                                                         --         27.2  16.7  25                                     2    PAS        --         0.3   83.2  70                                     3    PHS.sup.b  --         11.0  60.0  64                                     4    P(SAS)     90:10      8.6   76.7  84                                     5    P(SHS)     90:10      10.1  72.9  84                                     6    P(STFAS)   90:10      8.6   70.4  88                                     ______________________________________                                         .sup.a M.sub.1 is a molar ratio of the comonomer used with styrene;           .sup.b acetonitrile was used as the solvent in this case.                

It is evident from the results given in Table 4 that the polymericlayers are readily formed on aluminum foil. The contact anglemeasurements further show that the hydrophilic aluminum surface isconverted to hydrophobic surface after polymer treatment. This isevidenced by the fact that an increase in value of the contact angle ofup to 88° for the polymer treated aluminum foil was d when compared with25° for the untreated aluminum foil.

Example 7

The Example 6 is repeated using two cleaned aluminum foil samples andPHS as the polymeric material. These two PHS treated aluminum foilsamples were then used for further grafting experiments as follows. OnePHS treated aluminum foil sample was treated with a solution of 2 mL ofdimethyldichlorosilane in DMF (9 mL) in the presence of triethylamine (1mL) for about 24 hours at room temperature. A second PHS treatedaluminum foil sample was treated with 1,6-diisocyanatohexane (2 mL) intoluene (18 mL) at 60° C. under nitrogen for about 24 hours. After suchtreatment of the samples in both cases the samples were removed from therespective solution vials and rinsed with the respective solvents used,blown dry under nitrogen, and analyzed by XPS spectroscopic analysis. Aportion of both of these sample foils were also extracted with acetonefor 24 hours to determine if the grafted material can be removed byacetone extraction. The extracted samples were also analyzed by XPS. Theresults are given in Table 5. For comparison, the XPS data of thestarting PHS modified aluminum foil is also given in Table 5 (Run No. 1,Table 5).

                  TABLE 5                                                         ______________________________________                                        Run                     Atomic percentages (%)                                No   Description of Samples                                                                           C      O    Al   Si  N                                ______________________________________                                        1    PHS-modified aluminum foil                                                                       44.2   37.4 18.5 0.0 0.0                              2    PHS-modified aluminum foil                                                                       46.8   32.9 16.9 3.3 0.0                                   with dimethyldichlorosilane                                              3    Extracted PHS-modified aluminum                                                                  43.3   36.5 17.7 2.5 0.0                                   foil treated with dimethyldichloro-                                           silane                                                                   4    PHS-modified aluminum foil                                                                       59.7   24.9 11.3 0.0 4.2                                   treated with 1,6-diisocyanato-                                                hexane                                                                   5    Extracted PHS-modified aluminum                                                                  59.2   24.9 12.1 0.0 3.8                                   foil treated with 1,6-diisocyanato-                                           hexane                                                                   ______________________________________                                    

It is evident from the data presented in Table 5 that the product foilsare modified in that they contain either silicon or nitrogen based onthe grafting agent (Run Nos. 2 and 4, Table 5). Furthermore, very littleof these grafting agents were removed by extraction with acetone becausethere were only slight changes in atomic percentages after theextraction (Run Nos. 3 and 5, Table 5).

Example 8

The Example 6 is repeated except that the polymer used was a terpolymer,P(SASVBC). A portion of this terpolymer modified aluminum foil was thentreated with a THF solution of the sodium salt of monomethoxypoly(ethylene glycol) (Molecular weight 5000, PEG₅₀₀₀,) for 24 hours.After reaction, the foil was washed with water and acetone and thendried under a nitrogen atmosphere. Both of these samples were analyzedby XPS spectroscopy and by contact angle goniometry. The results aregiven in Table 6.

                  TABLE 6                                                         ______________________________________                                        Run                 Atomic percentages (%)                                    No   Description of Samples                                                                       C      O    Al   Cl  Na  Θa (°)              ______________________________________                                        1    P(SASVBC)-modified                                                                           62.3   23.2 13.4 1.1 0.0 82                                    aluminum foil                                                            2    NaPEG.sub.5000 /                                                                             48.2   36.1 15.2 0.3 0.2 54                                    P(SASVBC)-modified                                                            aluminum foil                                                            ______________________________________                                    

The data in Table 6 show that the hydrophobic surface of the aluminumfoil in Run No. 1 is modified to more hydrophilic surface in Run No. 2,as evidenced by the change in contact angle from 82° in Run No. 1 to 54°in Run No. 2. Furthermore, the amount of chlorine is decreased, andpresence of sodium is confirmed in Run No.2, thus confirming thereaction of terpolymer, P(SASVBC), with NaPEG₅₀₀₀ on the surface ofaluminum foil.

Example 9

The Example 6 is repeated except that the polymer used was a terpolymer,P(SASVBOCOCCl₃). One portion of the terpolymer treated aluminum foil wasthen treated with a 20 mL solution of acrylic acid in benzene (1 molarsolution--72 g of acrylic acid dissolved in 1000 mL of benzene), and inthe presence of Mn₂ (CO)₁₀ (0.005 g) and exposed to tungsten light atroom temperature for 2 hours. After this period, the foil was removedfrom the reaction mixture and washed with water and methanol and driedunder nitrogen.

Another portion of the terpolymer treated sample was similarly treatedwith a solution of methacrylonitrile in benzene (4 molar solution--268 gof methacrylonitrile dissolved in 1000 mL of benzene) in the presence ofMn₂ (CO)₁₀ (0.005 g) and exposed to tungsten light at room temperaturefor 8 hours. After this period, the foil was removed from the reactionmixture, washed with water and methanol, and dried under a nitrogenatmosphere. Both of these samples along with the starting aluminum foil,and the terpolymer treated aluminum foil were analyzed by XPSspectroscopy and contact angle goniometry. The results are given inTable 7. Also included in Table 7 are the results of two controlsamples, which were treated just with acrylic acid andmethacrylonitrile.

                  TABLE 7                                                         ______________________________________                                        Run                 Atomic percentages (%)                                    No   Description of Samples                                                                       C      O    Al   Cl  Na  Θa (°)              ______________________________________                                        1    Starting untreated                                                                           16.7   56.1 27.2 0.0 0.0 25                                    aluminum foil                                                            2    P(SASVBOCOCCl.sub.3)-                                                                        64.7   19.7 12.9 2.6 0.0 81                                    modified aluminum foil                                                   3    P(SASVBOCOCCl.sub.3)-                                                                        62.2   37.4 0.4  0.0 0.0 23                                    modified aluminum foil                                                        grafted with acrylic acid                                                4    Aluminum foil treated                                                                        48.7   40.5 10.8 0.0 0.0 22                                    with acrylic acid                                                             (control)                                                                5    P(SASVBOCOCCl.sub.3)-                                                                        42.1   39.8 14.8 0.0 3.4 77                                    modified aluminum foil                                                        grafted with                                                                  methacrylonitrile                                                        6    Aluminum foil treated                                                                        25.6   49.8 23.4 0.0 1.3 48                                    with methacrylonitrile                                                        (control)                                                                ______________________________________                                    

It is evident from the contact angle data presented in Table 7 that thehydrophobic surface of the aluminum foil in Run No. 2 can be modified toa hydrophilic surface by treatment with a suitable grafting agent asshown in Run No. 3.

Example 10

The Example 6 is repeated using PAS as the polymeric material. A portionof the PAS treated aluminum foil was then irradiated in XPSspectrometer. The irradiated sample was then extracted with acetone in aSoxhlet apparatus for about 48 hours. Similarly, a sample of PAS treatedaluminum foil, which was not irradiated was also extracted with acetonefor comparison. All of the samples were then analyzed by XPSspectroscopy. The results are given in Table 8.

                  TABLE 8                                                         ______________________________________                                                                    Atomic                                            Run                         percentages (%)                                   No.  Description of Samples C      O    Al                                    ______________________________________                                        1    Starting aluminum foil 16.3   55.2 28.5                                  2    PAS modified aluminum foil                                                                           81.4   17.4 1.2                                   3    PAS modified aluminum foil irradiated with                                                           74.8   19.2 3.0                                        XPS and extracted with acetone                                           4    PAS modified aluminum foil not irradiated                                                            41.6   39.3 19.1                                       with XPS and extracted with acetone                                      ______________________________________                                    

Although the invention has been illustrated by certain of the precedingexamples, it is not to be construed as being limited thereby; butrather, the invention encompasses the generic area as hereinbeforedisclosed. Various modifications and embodiments can be made withoutdeparting spirit and scope thereof.

What is claimed is:
 1. A polymeric material wherein it is a copolymer of a monomer selected from the group consisting of 4-thiocyanatomethylstyrene, 4-thiolmethylstyrene, 4-thioacetoxystyrene, and 4-trifluoroacetoxystyrene; and a styrenic derivative having the structure: ##STR5## wherein PEG is a polyethylene glycol moiety and d represents molecular weight of said polyethylene glycol moiety, which ranges from about 200 to about 10,000, and mixtures thereof.
 2. The polymeric material as set forth in claim 1 wherein said material has a number average molecular weight ranging from about 4,000 to about 100,000.
 3. The polymeric material as set forth in claim 2 wherein said copolymer contains a molar ratio of said monomer to said styrenic derivative within the range from about 1:99 to about 99:1.
 4. A polymeric material wherein it is a terpolymer of styrene; a second monomer selected from the group consisting of 4-hydroxystyrene, 4-acetoxystyrene, 4-thiocyanatomethylstyrene, 4-thiolmethylstyrene, 4-thioacetoxystyrene, and 4-trifluoroacetoxystyrene; and a third monomer having the structure: ##STR6## wherein PEG is a polyethylene glycol moiety and d represents molecular weight of said polyethylene glycol moiety, which ranges from about 200 to about 10,000, and mixtures thereof.
 5. The polymeric material as set forth in claim 4 wherein said material has a number average molecular weight ranging from about 4,000 to about 100,000.
 6. The polymeric material as set forth in claim 4 wherein said terpolymer contains on a mole basis from about 1% to about 98% of styrene; from about 2% to about 98% of said second monomer; and from about 1% to about 45% of said third monomer.
 7. The polymeric material as set forth in claim 4 wherein said terpolymer contains on a mole basis at least about 60% of styrene. 